<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="./vue-2.5.js"></script>
</head>
<body>
    <div id="app">

        <h1>总数:{{count}}</h1>
        <my-component @increase= "handleGetTotal" @reduce="handleGetTotal"></my-component>
    </div>

    <script>
    Vue.component('my-component',{
        template:`
        <div>
        <button @click='handIncrease'>+1</button>
        <button @click='handReduce'>-1</button>
        </div>
        `,
        data() {
            return {
                counter:0,
            }
        },
        methods: {
            handIncrease:function(){
                this.counter++;
                this.$emit('increase',this.counter)
            },
            handReduce:function(){
                this.counter--;
                this.$emit('reduce',this.counter)
            }
        },
    })

    let app = new Vue({
        el:'#app',
        data() {
            return {
                count:''
            }
        },
        methods: {
            handleGetTotal:function(count){
                this.count = count
            }
        },
    })
    </script>
</body>
</html>